Stromatolites, 3.5 billion-year-old creatures that collect in Patagonia, have a structure very similar to their ancient fossils — and have only now been found
December 14
2023
– 9:03 pm
(Updated at 9:55 p.m.)
Microbial communities that are some of the oldest life forms on the planet have been found in previously unknown Patagonian lakes, both living and fossilized. These are stromatolites, microscopic formations that reach large sizes when agglomerated. Her fossils are among The first evidence of the existence of living organismsThey are 3.5 billion years old – and the specimens seen in Argentina are particularly similar to their ancestors.
Many species use stromatolites to group together, the most common being cyanobacteria. These life forms produce oxygen, which is rare in Earth’s ancient atmosphere, so the first stromatolites may have been very different from those found today, made by sulfate-reducing bacteria. Both species form mounds of photosynthetic organisms that use their sand and fluids to harden and grow in search of sunlight.
Modern-day stromatolites reach over a meter in height, but are vulnerable to predators and other organisms that outgrow them. Therefore, these organisms generally can only survive where other life forms cannot, such as brackish water. The most famous are those from Shark Bay, Australia, who live next door Fossilized ancestors, among the oldest on the planet.
Primitive life in Patagonia
Puna de Atacama, in Patagonia, lies 4,000 meters above sea level, and its hypersaline lakes are home to an impressive discovery – one that has gone unnoticed by scientists even today. The remote area can only be found a 9-hour drive away on dirt roads, where responsible researchers are forced to stay in a village of 35 people fed only by a spring, as rainfall is too rare to guarantee the availability of liquid.
Satellite images revealed the lakes, located 16 kilometers from the village, were only visited on the scientists’ last day at the site, as the target of the study was other bacteria used in soil remediation. The 12 lakes occupy an area of 10 hectares (or 100,000 square kilometers) with transparent water, with very little life and mud. Peering down to the bottom revealed living stromatolites larger than anyone had ever seen, measuring 5 meters across and tens of centimeters high (although larger fossils have been found).
Chemical analysis of the interior revealed a unique composition, previously unheard of elsewhere – gypsum (CaSO42H2O), for the most part, which is common in fossil stromatolites but never seen in living specimens. The surface turns out to be composed of cyanobacteria, with a pink center due to the abundance of archaea, single-celled microorganisms without a nucleus that are strong candidates for the formation of authigenic stromatolites.
The place is extremely salty and acidic, and the lower atmosphere barely filters sunlight, very similar to early Earth, according to scientists. The Atacama Desert has been visited by many astrobiologists because it is the closest place to the ancient atmosphere of Mars. Studying organisms that survived or were fossilized in this environment helps us know what to expect when we excavate Martian rocks looking for signs of life.
However, scientists consider this discovery to be too late, as the Atacama is full of lithium. In the past, the material was despised, but it is now coveted by mining companies because it is an important component of batteries. The area is about to be drilled for deposits of the element, and that in itself could be enough to destroy the stromatolite system, a system that is very sensitive to changes.
source: Fall Conference of the American Geophysical Union, Mashable
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